The present invention relates to an optically active polymer of a chiral alkoxy-substituted phenylacetylene and a method for the preparation thereof. More particularly, the invention relates to an optically active polymer of an alkoxy-substituted phenylacetylene capable of exhibiting reversibly varied photoabsorption spectrum and/or photoemission spectrum as well as a method for the preparation thereof. Still more particularly, the optically active polymer has a unique steric structure of a spiral conjugated structure of a phenylacetylene compound substituted by an alkoxy group having chirality.
The inventors previously disclosed several polymers of substituted acetylene compounds, which are known to exhibit a structural change between a cis structure and a trans structure by way of the double bonds along the main chain of the polymer molecules. These conventional acetylene polymers, however, have problems relative to the stability in air due to their high susceptibility to oxidation by the oxygen in the atmospheric air and relative to their low controllability in the agglomeration behavior of the polymer chains. In this regard, the inventors have discovered that a polymer of an acetylene compound substituted by a specific group can be imparted with greatly increased stability against oxidation by virtue of its spiral structure which considerably inhibits conjugation along the direction of the main chain of the polyacetylene molecule.
A report is found in Kobunshi Kako (Polymer Processing), volume 50, No. 5, pages 221-223 (2001), in which a disclosure is given of a polymer of an acetylene monomer substituted by a p-nitrophenyl group or p-3-methylbutoxy group having a degree of polymerization in the range from 1.5 to 1440.0×103.
Further, a report is found in Macromolecules, volume 34, No. 11, pages 3776-3782 (2001) on a phenomenon that the above-described polymer of a substituted phenylacetylene exhibits a sift in the peak wavelength of the absorption spectrum from 430 nm to 460 nm as a result of the cis-trans transition caused by compression. It is also taught there that the above mentioned polyacetylene compound in the cis form is in an agglomerated form and the state of agglomeration is subject to changes by compression resulting in a shift of the peak wavelength of the absorption spectrum from 490 nm to 450 nm.
Relative to the disclosures in the above mentioned prior art documents, the inventors directed their attention to the effect of chirality of the substituent groups on the phenyl group of the phenylacetylene monomers and have continued extensive investigations along the line of this problem leading to establishment of the present invention based on their unique and unexpected discovery that, when the aforementioned polyacetylene compound is exposed to the vapor of a specific organic solvent, a novel polyacetylene compound is obtained which has a superspiral conjugation structure by the π electrons due to the double bonds.